[Rockhounds] Scapolite

[DonH]

Brother Axel,

I would imagine that crystallization of regular inorganic solids is more 
dependent on the conditions of formation.  If it has a well-defined 
structure, then under the right conditions it would tend to form 
crystals as large and well-shaped as any other.  This usually involves 
slow cooling and, of course, an abundance of the necessary elements or 
polyanions necessary to form the mineral.  Minerals formed from 
low-temperature alteration would tend not to form large and wel-defined 
crystals, though of course there may be exceptions to this.

To mineralogists, for example, gypsum brings to mind large crystals from 
  4 cm to huge crystals in the Cave of Swords.  To a soil scientist, 
gypsum usually brings thoughts of white crusts and nodules.

Best,
Don